Field of the Invention
The present invention relates to a hydraulic drive system.
Background Information
Work machines, such as a hydraulic excavator or a wheel loader, are equipped with a work implement driven by a hydraulic cylinder. Hydraulic fluid discharged from a hydraulic pump is supplied to the hydraulic cylinder. Hydraulic fluid is supplied via a hydraulic circuit to the hydraulic cylinder. For example, Japanese Patent Laid-open No. 2003-21104 describes a work machine equipped with a hydraulic closed circuit for supplying hydraulic fluid to the hydraulic cylinders. Potential energy of the work implement is regenerated due to the hydraulic circuit being a closed circuit. As a result, fuel consumption of a motor for driving the hydraulic pump can be reduced.